Temperature surfactants

Mineral acids are used as catalysts, usually in a concentration of 20— 40 wt % and temperatures of 30—60°C. An efficient surfactant, preferably one that is soluble in the acid-phase upon completion of the reaction, is needed to emulsify the a-pinene and acid. The surfactant can then be recycled with the acid. Phosphoric acid is the acid commonly used in the pine oil process. Its mild corrosion characteristics and its moderate strength make it more manageable, especially because the acid concentration is constandy changing in the process by the consumption of water. Phosphoric acid is also mild enough to prevent any significant dehydration of the alcohols formed in the process. Optimization of a process usually involves considerations of acid type and concentration, temperature, surfactant type and amount, and reaction time. The optimum process usually gives a maximum of alcohols with the minimum amount of hydrocarbons and cineoles. 

Schonherr J, Baur P (1996) Effects of temperature, surfactants and other adjuvants on rates of uptake of organic compounds. In Kerstiens G (ed) Plant cuticles an integrated functional approach. BIOS Scientific Publishers, Oxford UK, chap 6... 

The VRU is designed to treat soils contaminated with organic contaminants and heavy metals. The system is flexible, and allows for changes in the process train, treatment temperature, surfactant addition, and the use of steam for stripping. 

Below their phase transition temperatures, surfactants in SUVs are arranged in tilted, one-dimensional lattices they are in highly ordered solid states. Above the phase transition temperature, the surfactants are somewhat separated... 

The authors of this monograph consider reasonable to express foaming ability as the foam volume obtained from a known solution volume under defined conditions (temperature, surfactant concentration, mode of foam formation). As a more general characteristic of the ability of the surfactant solutions to form foams with a definite stability it is suitable to use the terms stabilising ability or foaming property. The volume of the foam obtained and its lifetime can serve as a qualitative measure for the latter. A more detailed estimation requires the use of a number of characteristics including drainage, internal foam collapse, etc. 

A particularly interesting part of the pilot involved the treating of produced emulsions. Over the life of the pilot, 93% of the injected surfactant was produced at the production wells, and this situation led to serious emulsion problems. Heating the emulsion to a specific, but unreported, temperature caused the surfactant to partition completely into the aqueous phase and leave the crude oil with very low levels of surfactant and brine. The resulting oil was suitable for pipeline transportation. The critical separation temperature had to be controlled to within 1 0. At higher temperatures, surfactant partitioned into the oil, and at lower temperatures, significant quantities of oil remained solubilized in the brine. Recovered surfactant was equivalent to the injected surfactant in terms of phase behavior, and had the potential for reuse. 

For the synthesis with nonionic block polymer as template, inorganic salts can dramatically widen the syntheses domain (in temperature, surfactant concentration, etc.) and broaden the range of surfactants that can be utilized to produce highly ordered mesostructures.[214]... 

Ziegler, V.M., 1988. Laboratory investigation of high temperature surfactant flooding. SPERE 3... 

Micelles can only form when the surfactant solubility is equal to or greater than the CMC. In general this occurs only above a particular temperature known as the Krafft point (temperature). Below this temperature surfactant solubility increases slowly with increasing temperature because the surfactant dissolves as monomers. The limit to monomer solubility occurs when the chemical potential of the monomers is equal to that of the pure (usually crystalline) surfactant. Above this temperature the solubility increases very rapidly because the surfactant dissolves as micelles the contribution of each micelle to the surfactant chemical potential being the same as that of a monomer. 

Historically, QDs were first synthesized in glass matrices where the slow difiusion of precursors provided some measure of size control. In the last couple of decades, colloidal techniques have advanced to the point that parameters such as precursor reactivity, temperature, surfactants etc. can be independently tuned to control and regulate nanocrystal formation. This enables the synthesis of high quality solvent dispersible particles that may be further processed using simple wet-chemical methods. Qne of the earliest techniques employed to achieve this is known as the arrested precipitation method where the semiconductor growth is arrested after the... 

Other factors can also affect the stability of foam among these are temperature, surfactant structure, surface viscosity, rate of drainage and bulk viscosity. 

Nystrom B, Kjoniksen A, Lindman B. Effects of temperature, surfactant, and salt on the rheological behavior in semidUute aqueous systems of a nonionic ceUulose ether, Langmuir 1996 12 3233-3240. 

Sonochemical Process Utilization of microcavities generated by ultrasonic cavitation. Chemical reactions occur in localized hot spots with short-lived high temperature and pressure Particle size control By ultrasonic power and fi equency, solvents, precursor concentration, pH, precursor materials, temperature, surfactants General attributes Mostly equiaxed shapes, some rod shape reported high degree of dispersion due to sonication... 

Because both melt-processing and polymerization of PET necessitate high temperatures (250-300 °C), it becomes obvious at the outset that any organically modified layered silicates that are intended as reinforcing fillers for PET should employ surfactants with appropriately high thermal stability. The typical alkylammoniums, for example, decompose below these temperatures. Two examples of higher-temperature surfactants that have been employed as modifiers for layered silicates in PET nanocomposites are pyridinium and phosphonium specifically, cetylpyridinium, via solution dispersion [22], and dode-cyltriphenylphosphonium, via in situ polymerization [23], In these two cases, both the... 

Figure 9.14. Pseudo-binary phase diagram of the water-oil-C/Ey system at equal water-to-oil volume ratios, representing the so-called fish-tail . This temperature-surfactant content T-y) representation is used to determine the temperature of the zero spontaneous curvature and the minimum amount of surfactant needed to include equal volumes of oil and water in a single-phase microemulsion...

In the case of P.Y. 139, the temperature, surfactant level and other parameters may be varied to obtain fine (Paliotol Yellow L 1820), medium size (Paliotol Yellow L 1970) and coarse products (Paliotol Yellow L 2140 HD) by selectively adjusting advanced finishing procedures and conditions. 

Various kinds of self-organizing structures are formed in polyoxyethylene-type nonionic surfactant/water systems depending on temperature, surfactant concentration, surfactant structures, etc. [1,2], In previous studies on the basic phase behavior of nonionic surfactants, dodecyl chain surfactants have been mainly used. In longer chain nonionic surfactant systems, more phases appear and they are more important for practical applications, although the phase behavior have not been extensively studied. Polyoxyethylene oleyl ethers are biocompatible surfactants used for cosmetics, medicines, etc. The purity of commercially available oleic acid (cis-9-octadecenoic acid) is usually around 60% and the rest contains more than 50 kinds of other fatty acids [3]. Since conventional commercial polyoxyethylene oleyl ethers are synthesized from the low-purity oleic acid, it is difficult to figure out the basic phase behavior of the nonionic surfactants in water. 

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